cfg80211: remove WARN_ON in __cfg80211_sme_scan_done

cfg80211_sme_scan_done() can be called (by fullmac cards) with
wdev->conn == NULL when CFG80211_SME_CONNECTING. We quit silently
instead of WARN_ON in this case.
Signed-off-by: NZhu Yi <yi.zhu@intel.com>
Acked-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/wireless/sme.c

@@ -227,7 +227,7 @@ static void __cfg80211_sme_scan_done(struct net_device *dev)
 	if (wdev->sme_state != CFG80211_SME_CONNECTING)
 		return;
 
-	if (WARN_ON(!wdev->conn))
+	if (!wdev->conn)
 		return;
 
 	if (wdev->conn->state != CFG80211_CONN_SCANNING &&